Lumbar isthmus cracking and spondylolisthesis

In the past, the causes of spinal fractures were classified into two categories: congenital and traumatic; but in fact, the most common are those caused by degenerative changes, accounting for more than 60% of all spinal fractures. Anatomically, the lumbar isthmus refers to the narrow part between the superior and inferior articular processes, where the bone structure is relatively weak. The normal lumbar spine has a physiological lordosis, the sacral vertebrae is physiologically kyphosis, and the junction of the lumbar and sacral vertebrae becomes a turning point. The upper lumbar spine is tilted forward, and the lower sacrum is tilted backward. Therefore, the negative gravity of the lumbar and sacral spine naturally forms a forward component, causing the waist 5 to slide forward. However, under normal circumstances, the lumbar 5 isthmus is at the intersection of the two forces due to the limitation of the lower 5 articular processes and the surrounding joint capsules and ligaments. Therefore, the isthmus is prone to collapse, which is the reason why the lumbar 5 isthmus has the most fractures. After the isthmus collapsed, the vertebral arch was divided into two parts. The upper part was the upper articular process, the transverse process, the pedicle, and the vertebral body, and remained in normal contact with the upper spine. The lower part was the lower articular process, lamina, spinous process, and the lower part. The sacrum is in contact. The bony connection was lost between the two parts, and the upper part was displaced forward due to the loss of restriction. The vertebral body slipped forward on the lower vertebral body.